1. Field of the Invention
The present invention relates to systems for fermentation. More particularly, the present invention relates to systems of fermentation that are continuous and stirred. The present invention also relates to systems for fermentation using algae as the microorganism.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98.
From the simplest to the most complex, biological processes maybe classified as fermentation, elementary physiological processes, and the action of living organisms. Fermentation is a biological reaction whereby a raw organic material is converted into a product by the action of microorganisms or by the action of enzymes produced by microorganisms. In a typical fermentation reaction, a raw organic material is fed into a reactor. The raw organic material can be any carbon-based material including, but not limited to, carbon dioxide, sugar products, sewage sludge, animal manures and cellulosic materials. Once in the reactor, the raw organic material is mixed with microorganisms or microbes that are suitably chosen for a desired reaction with the raw organic material. The group of microorganisms or microbes includes, but is not limited to, yeasts, bacteria, algae, molds, and protozoa.
A reaction occurs whereby a product is formed by mixing the raw organic material with the microorganisms. This product depends on the type of raw organic material used as well as the type of microorganisms or microbes used. The product of the fermentation reaction is typically recovered from the biomass of the reaction through various separation methods such as dewatering and floatation.
Fermentation processes are known as autocatalytic processes. The autocatalytic behavior of a fermentation process is represented by a sequence of events. First, when the raw organic material is first introduced into the fermentation reactor, there is only a small amount of catalytic microorganisms present in the reactor. Thus, the conversion of the raw organic material into product is slow, i.e., the rate of reaction is very low. However, as the concentration, or number, of microorganisms increases, the reaction rate rises, producing more microorganisms and more products. In a typical fermentation reaction, the reaction rate reaches a maximum followed by a gradual die-off of the raw organic material. At this point, there is very little raw organic material and a lot of product, so the rate eventually slows until there is no reaction.
Because of their nature, fermentation reactions are typically carried out in a batch reactor. Batch reactors involve reacting a finite amount of material from start to completion and then starting over with a new finite amount of material in the reactor. This type of reactor is in contrast to a continuous reactor that continuously reacts a continuous supply of material. Because batch processes inevitably have a reaction that ends, they have a high operating cost, high capital cost, complicated sequencing, and limited production capabilities. Thus, there is a need for systems allowing for continuous fermentation that have improved operating cost, capital cost, and production capabilities over batch operations.
In the past, various patents have issued relating to systems for continuous fermentation. For example, U.S. Pat. No. 6,599,735, issued on Jul. 29, 2003 to the Bartok et al., describes fermentation assembly comprising a vessel for culturing living cells, at least two storage flasks in fluid communication with the vessel for supply of liquids and a first transport means for transferring the liquids from the storage flasks to the vessel, individual appliances operably connected to the transport means for monitoring the supply of the contents of the storage flasks to the vessel, a harvest flask in fluid communication with the vessel and a second transport means for transferring the fermentation broth from the vessel to the harvest flask, and a device operably connected to the first transport means for controlling and maintaining a constant dilution rate in the vessel with varying rates of individual supply of liquid from the storage flasks to the vessel
U.S. Pat. No. 5,688,674, issued on Nov. 18, 1997 to Choi et al., describes a metabolite, e.g., ethanol, that is continuously produced from low cost carbohydrate substrates by a process which comprises pulverizing the carbohydrate substrate, liquefying and saccharifying the pulverized substrate, continuously fermenting the lique-saccharified substrate in a fermentor equipped with a moving filter, in the presence of flocculent biological cells maintained at a concentration ranging from 90 to 160 g/l by using the moving filter and a culture medium to produce a fermentation product mixture, and recovering the desired metabolite from the fermentation product mixture.
U.S. Pat. No. 4,069,149, issued on Jan. 17, 1978 to Jackson, describes a deep-tank reactor utilized for fermentation of waste liquid or other liquid in a biological reaction resulting in a solid cellular material. The resulting solid material, which is in suspension, is initially separated from the bulk of the liquid by a gaseous flotation process, using the dissolved gas in the liquid as the source of gaseous bubbles for flotation purposes.
U.S. Pat. No. 4,286,066, issued on Aug. 25, 1981 to Butler et al., describes an apparatus for continuously fermenting a moist particulate feed and distilling the fermentation product where a pressure-locked auger forces a moist particulate feed from a hopper into a fermentation tank. Liquor is removed from the tank, and solids are separated therefrom to produce a beer which is distilled in a distillation column. A combustion engine powers the auger and the means for separating solids, and the engine exhaust surrounds an inlet section of said auger to help heat the pressurized feed therein to produce fermentable sugar within the auger, and the auger includes a section passing to the tank in heat exchange relation to the distillation column to provide heat for distillation. The column is a multistage column angled to face the sun and has an upper glass plate to allow solar radiation to enter and penetrate between the foraminous plates of the column.
Research into efficient algal-oil production is currently being done in the private sector. Using algae to produce biodiesel may be a viable method by which to produce enough fuel to eliminate the dependence upon harvesting fossil fuels from non-sustainable resources. Algae require sunlight, carbon dioxide, small amounts of micronutrients, water, and small amounts of heat to grow. Given the proper conditions, some algae can double its mass in less than twelve (12) hours of fermentation. Importantly, algae can produce a portion their biomass in the form of oil. Because the algae grows in an aqueous suspension, they are capable of producing large amounts of biomass and usable oil in either high rate algal ponds or photobioreactors. This oil can then be processed into usable fuel.
It is an object of the present invention to provide a system for fermentation using algae.
It is another object of the present invention to achieve up to 80% reduction in the operating costs of batch fermentation processes.
It is another object of the present invention to provide a reactor design that optimizes the fermentation reaction.
It is another object of the present invention to extract oil from harvested algae using an economical method.
It is yet another object of the present invention to provide an optimal reactor structure for any given set of operating conditions.
It is still another object of the present invention to provide concentrated algae for more efficient collection.
These and other objects and advantages of the present invention will become apparent from a reading of the attached specification.